removeLoopClosures

Remove loop closures from pose graph

Syntax

removeLoopClosures(slamObj)

removeLoopClosures(slamObj,lcEdgeIDs)

Description

removeLoopClosures(slamObj) removes all loop closures from the underlying pose graph in slamObj.

removeLoopClosures(slamObj,lcEdgeIDs) removes the loop closure edges with the specified IDs from the underlying pose graph in slamObj.

Examples

Remove Loop Closures from Pose Graph in Lidar SLAM Object

Load laser scan data from a file.

load("offlineSlamData.mat");

To set up the SLAM algorithm:

1. Specify the lidar range, map resolution, loop closure threshold, and search radius.

2. Tune these parameters for your specific robot and environment.

3. Create the lidarSLAM object with these parameters.

maxLidarRange = 8;
mapResolution = 20;
slamObj = lidarSLAM(mapResolution,maxLidarRange);
slamObj.LoopClosureThreshold = 210;  
slamObj.LoopClosureSearchRadius = 8;

Add scans iteratively to the SLAM object.

for i = 1:numel(scans)
    addScan(slamObj,scans{i});
end

Create a copy of the SLAM object. Display the underlying pose graph of the SLAM object.

slamObj2 = copy(slamObj);
slamObj2.PoseGraph

ans = 
  poseGraph with properties:

               NumNodes: 71
               NumEdges: 83
    NumLoopClosureEdges: 13
     LoopClosureEdgeIDs: [31 36 63 65 67 69 71 73 75 77 79 81 83]
        LandmarkNodeIDs: [1×0 double]

Remove the first two loop closures by specifying their edge IDs.

lcEdgeIDs = slamObj2.PoseGraph.LoopClosureEdgeIDs(1:2);
removeLoopClosures(slamObj2,lcEdgeIDs)

Plot the pose graphs of the SLAM object before and after removing the loop closures.

subplot(2,1,1)
show(slamObj.PoseGraph);
subplot(2,1,2)
show(slamObj2.PoseGraph);

Input Arguments

slamObj — Lidar SLAM object

lidarSLAM object

Lidar SLAM object, specified as a lidarSLAM object. The object contains the SLAM algorithm parameters, sensor data, and underlying pose graph used to build the map

lcEdgeIDs — Loop closure edge IDs

vector of positive integers

Loop closure edge IDs, specified as a vector of positive integers. To find specific edge IDs, use findEdgeID on the underlying poseGraph object defined in slamObj.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Use this syntax when constructing lidarSLAM objects for code generation:

slamObj= lidarSLAM(mapResolution,maxLidarRange,maxNumScans) specifies the upper bound on the number of accepted scans allowed when generating code. maxNumScans is a positive integer. This scan limit is only required when generating code.

Version History

Introduced in R2019b